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Parallel manipulators present advantages compared to serial ones, such as higher load-carrying capacity, improved accuracy and increased stiffness. However, parallel manipulators possess limitations due to the presence of singularities. It has been proved that kinematic and actuation redundancy promote a significant reduction in the singularities and homogenization on the actuation forces. This paper evaluates the effect of the addition of kinematic redundancy in the energy efficiency of parallel manipulators. In order to do so, the required mechanical energy consumed by a 3RRR non-redundant planar parallel manipulator and their kinematically redundant versions, to perform several predefined trajectories is minimized using a genetic algorithm. The result of the comparison shows that the required mechanical energy to perform a given trajectory can be reduced with the addition of kinematic redundancy.

Parallel manipulators present high load capacity and rigidity, among other advantages, when compared to the serial manipulators. Due to their kinematic architecture, their parts are lighter. This characteristic may be an asset for designing high dynamic performance manipulators. However, parallel manipulators suffer from singularities in their workspace. This drawback can be circumvented by the use of kinematic redundancies. Due to the presence of these redundancies, the inverse kinematic problem presents an infinite number of solutions. The selection of a single solution among the possible ones is denoted as redundancy resolution. In this manuscript, the impact of several levels of kinematic redundancy on the dynamic performance of a planar parallel manipulator, the 3PRRR, is numerically and experimentally investigated. The kinematic redundancy of this manipulator can be added by the actuation of the active prismatic joints (P). Two redundancy resolution schemes are proposed using a multiobjective optimization problem. Based on the numerical and experimental results, one can conclude that the use of a proper redundancy resolution scheme can considerably reduce the maximum required torque to perform a predefined task.

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